Necroware on youtube just recently restored a similar mainboard: https://www.youtube.com/watch?v=eJ4DlRigKxA .

Your board is a Chicony CH-386-33H/40H. It has an entry in The Retro Web at https://theretroweb.com/motherboards/s/chicon … ch-386-33-40h-l

You can use an external battery instead of the integrated NiCd / NiMH barrel type battery by removing the jumper in JP1, and connecting an external voltage source (typically 3 - 4.5V is fine) to the outer two pins of JP1. The negative pole of the battery needs to be connected to the pin that is also connected to the negative pole of the Nickel rechargeable battery that you removed. As 3V is enough for the clock to operate, connecting a CR2032 to this connector is fine, as is connecting a 3*AA or 3*AAA battery holder with alkalines or NiMH low-self-discharge batteries. There is no charging voltage applied to the external battery connector, so you don't need to worry about Lithium or Alkaline batteries getting damaged by it.

mkarcher wrote on 2022-08-28, 11:41:

Necroware on youtube just recently restored a similar mainboard: https://www.youtube.com/watch?v=eJ4DlRigKxA .

Your board is a Chicony CH-386-33H/40H. It has an entry in The Retro Web at https://theretroweb.com/motherboards/s/chicon … ch-386-33-40h-l

You can use an external battery instead of the integrated NiCd / NiMH barrel type battery by removing the jumper in JP1, and connecting an external voltage source (typically 3 - 4.5V is fine) to the outer two pins of JP1. The negative pole of the battery needs to be connected to the pin that is also connected to the negative pole of the Nickel rechargeable battery that you removed. As 3V is enough for the clock to operate, connecting a CR2032 to this connector is fine, as is connecting a 3*AA or 3*AAA battery holder with alkalines or NiMH low-self-discharge batteries. There is no charging voltage applied to the external battery connector, so you don't need to worry about Lithium or Alkaline batteries getting damaged by it.

Excellent, thank you a lot, you gave me a lot of nice advice.

After completing the cleaning I will proceed with all the pass you wrote here to me.

Another big Thanks.

If anyone have other suggestion and comments please be kind to write!
Thanks!

Loris

Hi there,

so I cleaned the motherboard, and now after three days of dying procedure I decided the day has come.

I give it power.

I attach a photo about the situation, anyway after about 20 seconds that it has power the PC speaker emits a continuosly beep.

What can I do now?

As you can see I haven't connected any expansion card, any VGA ISA card.

PS: I have no led on the keyboard.

This is the situation around the barrel battery that I have removed and replaced with this new CR2032.

We can see some traces ruined, but If I check continuity with multimeter we have it.

I don't know what to think, anyway the keyboard never showed up the LED, I never seen a led from the keyboard.

This is why the PC Speaker after a thirty seconds around short beeps continuosly?

biessea wrote on 2022-08-31, 15:08:

I don't know what to think, anyway the keyboard never showed up the LED, I never seen a led from the keyboard.

This is why the PC Speaker after a thirty seconds around short beeps continuosly?

You are giving some important clues: Most AT keyboards (and PS/2 keyboards with adapter) blink their LEDs as soon as you apply power. No keyboard LED might indicate that the keyboard doesn't get enough power. If I am not completely mistaken, the keyboard connector should receive +5V via F1 (a fuse that was substituted by a wire, probably already at manufacturing) and L1, and it should receive GND via L3. Make sure that you have conductivity from the corresponding power supply pins to the keyboard connector pins.

PC Speaker sound after thirty seconds surely indicates that the processor is executing BIOS code, because something has to wait for 30 seconds and then enable the beep. This means the "core" of the board seems to be working. A keyboard that doesn't get power can irritate a mainboard (especially the keyboard controller) well enough to cause all kinds of strange behaviour, so I recommend you to try to fix the keyboard power issue first, and re-test the behaviour afterwards.

Throw on a graphics card to see if that helps-- it's not going to boot very far without a graphics card.

AlaricD wrote on 2022-08-31, 15:47:

Throw on a graphics card to see if that helps-- it's not going to boot very far without a graphics card.

As the board has an AMI BIOS: Missing graphics cards is indicated by 8 beeps (possibly prefixed by some "intro beeps" in a different pitch). A continous beep is more serious than a missing graphics card. Yet, the advice is still good: A graphics card will be needed soon.

mkarcher wrote on 2022-08-31, 15:37:

biessea wrote on 2022-08-31, 15:08:

I don't know what to think, anyway the keyboard never showed up the LED, I never seen a led from the keyboard.

This is why the PC Speaker after a thirty seconds around short beeps continuosly?

You are giving some important clues: Most AT keyboards (and PS/2 keyboards with adapter) blink their LEDs as soon as you apply power. No keyboard LED might indicate that the keyboard doesn't get enough power. If I am not completely mistaken, the keyboard connector should receive +5V via F1 (a fuse that was substituted by a wire, probably already at manufacturing) and L1, and it should receive GND via L3. Make sure that you have conductivity from the corresponding power supply pins to the keyboard connector pins.

PC Speaker sound after thirty seconds surely indicates that the processor is executing BIOS code, because something has to wait for 30 seconds and then enable the beep. This means the "core" of the board seems to be working. A keyboard that doesn't get power can irritate a mainboard (especially the keyboard controller) well enough to cause all kinds of strange behaviour, so I recommend you to try to fix the keyboard power issue first, and re-test the behaviour afterwards.

Thanks a lot, I am thinking about that, the keyboard has no power. And problably mess around the motherboard.
How can I fix if it has no power?

PS: I don't have a ISA video card, I'm probably buying soon, I wanted to be sure that the mobo is working beforce spend 30 bucks for a nice Tseng labs et4000ax that I have found on italian Ebay.

It looks like there's battery damage left to deal with, most likely some bad traces under sockets and connectors...

Tiido wrote on 2022-08-31, 18:02:

It looks like there's battery damage left to deal with, most likely some bad traces under sockets and connectors...

I used the vinegar two times, I cleaned with water and soap...I don't think the PCB has other acid there...it seems some traces are like opened... but I'm not sure that is the problem.

biessea wrote on 2022-08-31, 17:29:

Thanks a lot, I am thinking about that, the keyboard has no power. And problably mess around the motherboard.
How can I fix if it has no power?

You need to find out where the power is interrupted. You need to understand that your mainboard consists of four layers of traces. You can easily see the traces on the top and on the bottom of the board. The two inner layers actually are power planes. They are solid areas of copper with small holes in them. One of the inner layers is connected to ground and the other one is connected to +5V. As you get beeping, +5V and ground are definitely getting around on the board, so the power planes themselves seem to be powered.

For the keyboard supply, the outer edge of the wire labelled "F1" is connected to the +5V plane. On the back of the board, a trace from other end of F1 runs to one end of L1, and the other end of L1 is connected to one pin of the keyboard connector. Also, the end of L3 that is farther away from the keyboard connector is connected to the ground plane. The end of L3 that is closer to the keyboard connector is connected to a pin of the keyboard connector via a trace on the top of the board. That trace might be broken right next to the keyboard connector. You need to check continuity between +5V on the power plane (e.g. a +5V connector of the AT power supply) and the pin and the keyboard jack that should carry +5V. You also need to check continuity between GND (e.g. one of the center pins of the AT power supply connector) and the keyboard jack pin that is connected to L3. If you don't have a tool to check continuity, go buy any multimeter. While there are a lot of deficiencies on budget ($5-$10) multimeters, they generally work for continuity tests and probing around in low voltage circuits like computers.

If you find the place where the power delivery is interrupted, you need to fix the trace or solder a wire to the board as replacement for the broken trace.

mkarcher wrote on 2022-08-31, 18:52:

You need to find out where the power is interrupted. You need to understand that your mainboard consists of four layers of trace […]
Show full quote

biessea wrote on 2022-08-31, 17:29:

Thanks a lot, I am thinking about that, the keyboard has no power. And problably mess around the motherboard.
How can I fix if it has no power?

You need to find out where the power is interrupted. You need to understand that your mainboard consists of four layers of traces. You can easily see the traces on the top and on the bottom of the board. The two inner layers actually are power planes. They are solid areas of copper with small holes in them. One of the inner layers is connected to ground and the other one is connected to +5V. As you get beeping, +5V and ground are definitely getting around on the board, so the power planes themselves seem to be powered.

For the keyboard supply, the outer edge of the wire labelled "F1" is connected to the +5V plane. On the back of the board, a trace from other end of F1 runs to one end of L1, and the other end of L1 is connected to one pin of the keyboard connector. Also, the end of L3 that is farther away from the keyboard connector is connected to the ground plane. The end of L3 that is closer to the keyboard connector is connected to a pin of the keyboard connector via a trace on the top of the board. That trace might be broken right next to the keyboard connector. You need to check continuity between +5V on the power plane (e.g. a +5V connector of the AT power supply) and the pin and the keyboard jack that should carry +5V. You also need to check continuity between GND (e.g. one of the center pins of the AT power supply connector) and the keyboard jack pin that is connected to L3. If you don't have a tool to check continuity, go buy any multimeter. While there are a lot of deficiencies on budget ($5-$10) multimeters, they generally work for continuity tests and probing around in low voltage circuits like computers.

If you find the place where the power delivery is interrupted, you need to fix the trace or solder a wire to the board as replacement for the broken trace.

Hey, thank you SO much for all these hints.
I admit I have to read them a lot of times ot understand well, I love computer world and I love to make a lot of things with them, like video card bioses, like overclocking, but I admit this is a board too old for me.
Anyway listening PC speaker sing ignite on me a little smile.
I have a nice multimeter yes, a good FLUKE 15B. And yes, I can try to check continuity between traces.

But please, expalain me better, I cannot really understand L3, L1, F1, I don't really know what you are speaking about my dear.

I think that together we can go on and finally solve that problem, so I can have a nice rare motherboard and a lot of people can be jealous 😉

Please, explain me better, tell me what I have to do.

Thanks a lot, another time.

PS: I am buying a VGA ISA card.

Loris

biessea wrote on 2022-08-31, 21:34:

But please, expalain me better, I cannot really understand L3, L1, F1, I don't really know what you are speaking about my dear.

L1, L3 and F1 are components designators. Take a close look at your board. You will notice that next to each component, there is a small white printed text that names the component. The letter is the component type (F for fuse, L for inductor), and the number is usually just counting all components of that type. The components I named are all right next to the keyboard connector.

biessea wrote on 2022-08-31, 21:34:

PS: I am buying a VGA ISA card.

If the market didn't change a lot the last days, getting an ET4000AX card at 30 bucks (€ or USD) in the USA or (western) Europe is a great price. If you are located in that region or a region with similar pricing, and you need an ISA VGA card, go get it

Notice the empty socket for crystal oscillator. You will need one for the mobo to light up.
This board is all right. You will have fun time onlining it. It will function ok at 40MHz, but don't expect more than that.
With that said - i hope it is still alive actually after all these years.

mkarcher wrote on 2022-08-28, 11:41:

[...]
Your board is a Chicony CH-386-33H/40H. It has an entry in The Retro Web at https://theretroweb.com/motherboards/s/chicon … ch-386-33-40h-l
[...]

I'd rather say that this is Chicony CH-386-33/40H(L)
https://theretroweb.com/motherboards/s/chicon … -486dlc-33-40h-
It has UMC chipset instead of OPTI. It's name is almost the same...

pshipkov wrote on 2022-09-01, 06:44:

Notice the empty socket for crystal oscillator. You will need one for the mobo to light up.

The label at the empty socket seems to indicate that that it should be populated with a crystal for 30 or 33MHz CPU clock. The required 80MHz oscillator for 40MHz is present. I consider it possible that the board will work at 40MHz CPU clock even without that oscillator.

It can work at up to 45mhz i think.

pshipkov wrote on 2022-09-01, 06:44:

Notice the empty socket for crystal oscillator. You will need one for the mobo to light up.
This board is all right. You will have fun time onlining it. It will function ok at 40MHz, but don't expect more than that.
With that said - i hope it is still alive actually after all these years.

Are you su about this?

Another user said me that this empty socket doesn't permit to power on the mainboard.
Other said that this socket can be left empty for using the card in standard mode.
So please, we have to be sure about that, cause it is useless that I see the solder ways, I try to repair thing that doesn't be the point cause the mobo doesn't work.
If I have to find that cristal I think the task will be probably impossible.

Can someone assure me about that?

Thanks.

And thank for the explaination about components naming.

So I have to check the conducibility of these ways near the keyboard socket.

I may be wrong. Cannot remember anymore. Stick with the existing crystal oscillator first and if things are really no go fuss around with the second one.